Patent Literature 1 (identified below) discloses an RFID tag in which an RFIC (Radio Frequency Integrated Circuit) element is mounted on a base material including a conductor pattern functioning as a dipole antenna. This RFID tag is attached to an article for the sake of logistics, for example, and reading and writing is performed by a reader/writer when necessary.
The dipole antenna includes two dipole elements to be connected to two connection ends of an RFIC element. Therefore, a null point, at which gain is zero, occurs in a direction in which the two dipole elements extend from the two connection ends of the RFIC element to respective open ends. A reader/writer is not able to communicate in a direction of this null point.
Patent Literature 1: Japanese Patent No. 5904316.
The presence of the above described null point usually does not cause a problem since the direction of a reader/writer is flexible with respect to an RFID tag when the RFID tag is used in order to manage a certain article. In other words, when communication is not able to be established at a distance within which communication with the RFID tag must be enabled, a null point is able to be avoided only by slightly changing the direction of a reader/writer with respect to the RFID tag, so that communication is enabled.
However, when a position at which the RFID tag is able to be attached to an article is limited, or when the direction of a reader/writer to an article (with respect to an RFID tag) is limited, the above-stated null point may cause a serious problem. In other words, when the RFID tag is attached to an article at the only attachable position in the only attachable direction, and a reader/writer is held over the article in the only possible direction, communication is not established and the RFID tag is not able to be used practically.